And I'm Melissa Block. Time is of the essence. Those words about Syria today from a United Nations spokesman as tanks and armored vehicles launched new attacks on the city of Daraa. Syrian forces are also bombarding the city of Idlib. The U.N. says nearly 8,000 people have been killed so far during the uprising against Syria's President Bashar al-Assad.

SIEGEL: There is plenty of international condemnation of Syria's actions, but there is still no agreement on what should be done. The U.S. has called for Bashar al-Assad to go but for the moment advocates more time for diplomacy.

BLOCK: We're going to spend some time considering the options for Syria with three former U.S. officials, and we begin with Anne-Marie Slaughter, who recently left the State Department. She supports a plan to create no-kill zones for the Syrian people.

ANNE-MARIE SLAUGHTER: It would declare as safe zones, as no-kill zones, places where right now the opposition is in control, and it would do it all at once as part of an actual plan that would say, look, we're putting in some arms, a lot of intelligence, a lot of communications equipment, in the service of a plan that is basically saying, look, these are peaceful zones. There's nobody shooting at the Syrian army from these zones. It would say to Assad, you know, you overrun these zones, and you are simply slaughtering people who are not shooting at you.

We've got to do this fast because the momentum, I think, has shifted to Assad. At this point he's taking on one city at a time and rolling them up. And I think he's pretty convinced he can do that. And we really right now are doing nothing.

BLOCK: If you were to establish these no-kill zones, safe havens, they would need to be defended, right? They'd need to be armed. The Syrian army has been using tanks, heavy artillery. We're not talking about just handing out Kalashnikovs. What would they need - what would the opposition need to defend itself?

SLAUGHTER: Well, there are two advantages of these zones. One is, if you establish them, there are a lot of people inside Syria who think you'd get many more defections from the Syrian army because they'd have a safe place to go. And right now they don't have that. But the second point, it's true that at this point, given what Assad is willing to do, I think you might well have to have air power from - again, from Turkey, from Qatar, Saudi Arabia, and probably some NATO forces, to at least target tanks massed outside a town, mortar emplacements, and that would mean taking out air defenses. It would be a statement that we are going to prevent the slaughter of innocent civilians.

BLOCK: And would you say that the U.S. should be involved in that air campaign that you're suggesting?

SLAUGHTER: If the Arab League and Turkey approve the plan I'm putting forward, then yes. Then I think the U.S. and other Western countries should support a regional initiative to do this. If we don't do this, I think we're looking at a scenario where the first dictator who has been willing to pull out all the stops to crush what was a peaceful opposition is going to win.

BLOCK: You've said that the military aid should be used by the rebels only defensively - in other words, no revenge attacks, no offensive action. How would you control that?

SLAUGHTER: Well, you can't control that completely, but the point is that you would have a plan whereby a number of countries come together and say we are supplying, first of all, intelligence, communications, assistance of all kinds and weapons enough to defend these zones on these conditions. That's a very different thing than simply sending in arms to different rebel groups, which is what is happening now, and there's no point of contact. There's no point of communication, and of course that people are then free to use these arms however they want.

BLOCK: Professor Slaughter, what if the window of opportunity has closed? That if you look at the crackdown in Homs and in Idlib and then Daraa, is it possible that the scenario if it had merit, it's now too late?

SLAUGHTER: I do think the window is closing. If it closes, then what we have to be prepared to accept is that this is a government that decided it would do whatever it took to stop the political opposition - brutality on an extraordinary scale - and the world stood by and let it do it.

BLOCK: That's Anne-Marie Slaughter of Princeton University, formerly the State Department director of policy planning under President Obama.

Now to Paul Wolfowitz. He was U.S. deputy secretary of defense and a key strategist in the Iraq War under President Bush. He argues for direct assistance to the Syrian opposition, including weapons.

PAUL WOLFOWITZ: We should be supporting the opposition in every way reasonable, which doesn't mean bombing Damascus, for example, or occupying Syria. It does mean providing them with financial support, with material support, communications assistance - where I think we're doing a little bit, but I don't think we're doing everything we could do - and yes, weapons. I would say defensive weapons. There's no need for tanks. There's no need for artillery. And particularly, I think, to provide some encouragement for Syrian army units to defect. They're not going to be comfortable defecting into the hands of unarmed rebels.

BLOCK: You do hear this from people who say that arming the opposition is a bad idea. That it will lead to all-out civil sectarian war in Syria.

WOLFOWITZ: We heard the same argument for three years in Bosnia, and what it led to was prolonging - it is a civil war already, except it's one side fighting. It's Assad killing his own people. In fact, it dignifies Assad in a way to call it a civil war. But, yes, there are some significant number of Syrians on his side. It's terrible what is happening there, but it will only go on longer and be worse if we continue to take a hands-off position. And there's the real possibility that Assad will win. And I can't imagine a worse outcome than that.

BLOCK: Do you think the United States, in particular, should be supplying those weapons?

WOLFOWITZ: I think it'd much better if we're involved in the supply than if we leave it to people whose motives and objectives may be very different from ours and in some cases quite opposite to ours. You know, this situation is moving. It's been over a year now. We see Syrian demonstrators actually holding up signs complaining about American procrastination. And Hamas, which used to be in bed with Assad, has now distanced itself from the Assad regime. I'm sure the bad guys are figuring out how they can help the opposition so that they can have a position later. The United States, I think, should be leading a coalition of people who, more or less, share our objectives in the situation, not leaving it for others.

BLOCK: Leading a coalition. Would you say that any action should be authorized by the Security Council? Should it be - should the Arab League or Turkey take the lead?

WOLFOWITZ: I think Russia and China made it clear the U.N. Security Council isn't even going to authorize a severe reprimand of Syria. But the Arab League is already very much in the lead. Saudi Arabia is out in front of the United States. Turkey's position is a little hard to read, but I would say they're quite active. And every one of these countries will be more active if they feel they're not alone.

BLOCK: I'm curious. As one of the architects of the Iraq War, do you draw lessons about the limits of U.S. military intervention in conflicts overseas?

WOLFOWITZ: Of course, there are limits to U.S. military intervention. And no one I know of for two seconds would suggest that Syria is Iraq and that we should be involved in Syria the way we were involved in Iraq, or that we see Syria as a kind of threat to the United States that we saw Iraq being. But I also think there are many situations, including, in my own opinion, Iraq in 1991, where we have failed to support people who were ready to fight for themselves. And as a result, we ended up becoming more involved, not less involved. I think it's much better when people want to fight for their own freedom, to help them to do that, than to end up having to come in ourselves later.

BLOCK: That's former Pentagon official Paul Wolfowitz, currently at the American Enterprise Institute.

Lastly, a very different take on what to do about Syria from Daniel Serwer. He was U.S. special envoy to Bosnia during that military intervention in the 1990s. He says Syria needs a political solution.

DANIEL SERWER: I think we have to make a breakthrough at the U.N. Security Council. I don't think Bashar al-Assad will last long the day the Russians tell him that he has to go. And the question on my mind is what do we need to do to get the Russians to tell him that?

Kofi Annan, whose mission is failing at the moment - his diplomatic mission is failing. Why? Because he has no backing of the Security Council. He has no resolution to work with. He needs one.

BLOCK: Well, let's talk about that because Russia and China both have been blocking any action at the Security Council. There just seems to be no will at all, despite lots of months of pressure on them to change.

Kofi Annan goes to Syria, comes back with nothing. Bashar al-Assad basically thumbs his nose at that mission. Why would you think that diplomacy could still work?

SERWER: Diplomacy takes time. It doesn't work instantaneously. But military assistance takes time, too. I don't believe that there is a military solution in Syria without a massive U.S. effort to defeat the air defenses, the artillery, the tanks of the Syrian army and I see no will in Washington to do that kind of thing at the moment.

BLOCK: If there were will, would you support it, similar to the bombing campaign in Libya?

SERWER: I'd still have a lot of questions to ask about it. I need a political plan, as well as a military one. And the military - you know, everybody keeps on talking about humanitarian corridors and this kind of thing. They've never worked. They're not safe areas. They have to be made safe and they're made safe by military force.

You know, if you take military action, I think you have to think about taking serious military action. And serious military action would be aimed at decapitating this regime. The problem is you don't know what comes after because there is no really consolidated opposition political structure.

BLOCK: Daniel Serwer, I was looking at a piece you wrote in The Atlantic under the headline "Why the Syrian Rebels Should Put Down Their Guns." And you talked about your support for nonviolent protest even now. You raised even - and I was shocked to read this notion - banging pans at a fixed hour of the night is a tried and true protest technique. Banging pans? Is that what you're suggesting for the Syrian opposition?

SERWER: I'd suggest anything for the Syrian opposition that's relatively safe for them. I don't think that anything they do that puts large numbers of lives at risk is a good idea.

As long as the government can crack down and not undermine its own legitimacy because it can claim that there are some people shooting at us - as long as that's going on, the number of people willing to go into the street, bang pans, do whatever you like is going to be very limited.

Success in nonviolent resistance comes from numbers, large numbers, and so you've got to make it relatively safe for people to do whatever you're asking them to do.

BLOCK: That's Daniel Serwer, now professor at the Johns Hopkins School of Advanced International Studies. We also heard from Paul Wolfowitz and Anne-Marie Slaughter. Three voices on what to do about the bloodshed in Syria. Transcript provided by NPR, Copyright National Public Radio.